Ignore pending_signals when checking for quits.

pending_signals is often set if no quit is pending.  This results in
bugs in module code if the module returns but no quit is actually
pending.

As a better alternative, add a new process_input environment function
for Emacs 27.  That function processes signals (like maybe_quit).

* configure.ac: Add module snippet for Emacs 27.

* src/module-env-27.h: New file.

* src/emacs-module.h.in: Add process_input function to environment
interface.

* src/emacs-module.c (module_should_quit): Use QUITP macro to check
whether the caller should quit.
(module_process_input): New function.
(initialize_environment): Use it.

* src/eval.c: Remove obsolete comment.

* test/data/emacs-module/mod-test.c (signal_wrong_type_argument)
(signal_errno): New helper functions.
(Fmod_test_sleep_until): New test module function.

* test/src/emacs-module-tests.el (mod-test-sleep-until): New unit
test.

* doc/lispref/internals.texi (Module Misc): Document process_input.

1 files changed, 3 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 67e376d9b38..8acbf6d3a7f 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1614,6 +1614,9 @@ given frame supports resizing.
 This is currently supported on GNUish hosts and on modern versions of
 MS-Windows.
 
+** New module environment function 'process_input' to process user
+input while module code is running.
+
 
 * Changes in Emacs 27.1 on Non-Free Operating Systems